The object of this project is to develop a system to study the transformation of bloodstream trypanosomes into procyclic culture forms that is amenable to biochemical studies. Bloodstream forms are grown in the presence of a feeder layer of mammalian cells and then allowed to transform into procyclic forms in vitro. Various parameters of this system will be examined, including the role of protein and RNA and DNA systhesis, transcriptional activity of kinetoplast maxicircle and minicircle DNA, and mitochondrial enzymatic changes.